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Sturdy Cosmos plants but no flowers

Novice23Novice23 Posts: 200
in Plants
I grew Cosmos from Sarah Raven seeds this year, (can't remember the variety as the packet is long gone) and they are wonderful strong and sturdy plants, growing to about 54 inches. But not a single flowers on any of them.   I have watered well, they are in full sun and not crowded out.   So disappointing. 

I see there was a similar thread a couple of years ago and wondered if anyone can offer any reason for this.

Many thanks
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Posts

  • B3B3 Posts: 27,505
    I think we decided that they flower better and sooner in poorer soil.
    You will get flowers eventually and a probably great display until the frosts. 
    In London. Keen but lazy.
  • Novice23Novice23 Posts: 200
    Thanks, I have been contemplating digging them up, but will wait and see what happens.  
  • rock_henrock_hen Posts: 106
    Same here. Some of mine are flowering though the great majority of them are huge bushy plants with no sign of buds. I resisting the urge to pull them up just yet...
  • LynLyn Posts: 23,190
    If we don’t get a frost they can bloom up to November,  don’t give up just yet, it’s still only August.  
    Gardening on the wild, windy west side of Dartmoor. 

  • Blue OnionBlue Onion Posts: 2,995
    @Fire had this same issue in previous years.. did you find a solution Fire?

    I've never had any issues with them, either here or in the UK.  But I didn't feed them and both locations have been fairly dry and free draining (green sands of Surrey, and Utah). 
    Utah, USA.
  • LatimerLatimer Posts: 1,068
    I've had the same issue though I must say it's very random! Some have started flowering a couple of weeks ago while others, sown at the same time are just starting and others still have no sign of flowers. Mine are all planned in pots in different places around the garden though!
    I’ve no idea what I’m doing. 
  • FireFire Posts: 19,096
    Yes, I had the same issues when they went a) very late and b) into recently manured ground. Mine started flowering in October and had time that year to flower their socks off until the late frost. They will also take a bit of frost, unlike, say, dahlias or begonias, I have found, so cosmos won't be slayed straight off by a mild frost. The cosmos had become small trees by Oct and filled the small garden. It was amazing to see shocking pink flower trees shining out when most of the other plants had gone to bed. Worth doing it that way, almost, for that.
  • VoyagerxpVoyagerxp Posts: 651
    My dwarf cosmos have gone mad, i thought they would have been smaller.


  • sarinkasarinka Posts: 270
    All my dwarf cosmos are massive and still only 2 out of 14 have deigned to flower. The two that have have been 1) in the unenriched soil on the northfacing fence and 2) on the very edge of a new border, where the manure may not have reached.
  • punkdocpunkdoc Posts: 15,039
    I think the point that a lot of people do not appreciate, is that Cosmos are short day flowers. They flower best when the night is 12 hours long, which does not happen in an English summer.
    One thing that can help, is to save seed from plants that do flower, these will produce plants that are more likely to flower over here.
    How can you lie there and think of England
    When you don't even know who's in the team

    S.Yorkshire/Derbyshire border
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